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From: mouse@larry.mcrcim.mcgill.EDU
Newsgroups: comp.windows.x
Subject: Re: No expose after map if backing store?
Message-ID: <9101241107.AA16318@Larry.McRCIM.McGill.EDU>
Date: 24 Jan 91 11:07:26 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 24

>>> As anybody knows, before drawing to a window just mapped one has to
>>> wait for an exposure event. Fine.
>>> But why does the program below hang on R4 servers with backing
>>> store and runs fine on servers without?
>> I suggest that rather than just asking for ExposureMask you also ask
>> for StructureNotifyMask and proceed after a MapNotify event.  Asking
>> for ExposureMask is still a good idea since the server may generate
>> exposures instead of offering backing store.
> It's been my experience that if the server provides backing store it
> may send you an Expose event even before mapping the window.
> Wouldn't waiting for an Expose event following a MapNotify
> potentially not work?

Perfectly true.

So why mess with MapNotify events at all?  Just draw when you get an
Expose.  Clean and, provided you take care that the window is created
with ExposureMask selected, foolproof despite servers changing their
minds on the fly about supporting backing-store....

					der Mouse

			old: mcgill-vision!mouse
			new: mouse@larry.mcrcim.mcgill.edu